fasty

Hi,

I am looking for location in my 2003 RX300 "MPX computer" controlling km/miles display. http://www.cbss.ca/images/eStore/RX300-mpx.jpg

I have US (Miles/Fahrenheit) version and understand that by replacing MPX with metric I can get kilometers and Celsius display. Anybody have and experience or cost involved with this project?

Thanks in advance

Edward

Lexmex

In all my years here, I don't think I have ever seen someone actually go ahead and do it this way, though I am aware of some in Russia having done something similar to what you are describing in order to switch to metric.

fasty

Reason I asked is that I seen at eBay that MPX computer is selling in US, he says it comes with instruction and it takes 5 min to do it. He also ask to send old module for exchange.

fasty

At least anybody knows where can I find it in my car? I need part number that I can order from Toyota/Lexus dealer.

Edward

salimshah

I fail to understand why people don't call the dealership/parts department for a part number. The parts over time can be improved and old parts can be retired. There are added advantage that if the part is wrong, the dealer will take it back.
[that is if you choose to order through them ... maybe for a higher price].

I have had excellent service and have witnessed the helpfulness of the parts staff here in Lexus of Austin.

If you ask the members, you run the risk of unintended wrong guidance.

Salim

fasty

You are right, but at least I would have better idea what I am talking about when ordering, those module I understand are not very common. Other thing why I would like to know where it is, that I can possibly replace it on my own, but I have to find it and estimate difficulties.

Edward

fasty

I just got of the phone to my local Lexus part department, they can only suggest to change whole dashboard, $3,000, but he also mention if I come up with part # he would be able to look it up. From my picture I can't really read full number anybody could help to get that number, please?

bob2200

Going only by the picture, and my sketch-to-parts-number diagrams (i.e., I could be wrong); it looks like the Multiplex Computer:

99-00 89221-48080
01-02 89221-48031

Wassum3636

salimshah

Pardon my ignorance but can some one expand the term MPX body control? Is there an alternative (more commonly used) word(s) for it.

Salim

Margate330

-> Someone would need to verify that the Body ECU(multiplex computer/MPX computer) is responsible for the job of doing this. F/C and miles/km.

-> Too vague, 5 minutes to do what exactly? Is the seller saying it is a 5 minute job to install it or 5 minute job to change the settings. If he is saying it is a 5 minute job to install it and requiring the old one to be sent in for swap out, the seller is probably selling a used Body ECU reflashed for country/region-needed to change from F ot C.
But, until someone does this and reports success I wouldn't count on an ebay listing as 100% proof this setting from F to C is managed by the Body ECU yet...

-> From what this person is reporting from the Lexus dealer implies that the setting from F to C is done by the ECU's on the circuit boards in the dash cluster behind the speedometer and not the Body ECU- but still inconclusive...


-> Pictured above is the location of the Body ECU, in some countries it may be called a "Multiplex Computer" or MPX computer.


Hi members, I am unable to find exactly where the settings from F to C can be changed for our cars. It appears the RX300 has a dedicated Body ECU for the car's interior data network bus.
On the RX330 this has been integrated into the fuse panel/junction box under the steering wheel- I like RX300 design better.
-> If someone ever figures out where the settings can be changed hopefully they will post the info. But as can be seen above, the info on this is contradictory- is it in the Body ECU(multiplex computer) or the dash cluster ECU's? Maybe it's in the Engine ECM, that's always a possibility too.

Here is a pic I made showing how the Body ECU commuicates thru a single wire to the other ECU's such as the Engine ECM, Dash Cluster, Body ECU- any of which can hold the key to the question- where is the settings need changed?


-> Has anyone tried changing F/C and miles/km settings in Techstream? maybe it's that easy, I don't know.

salimshah

Thank you Margate330.

If we are talking Km & C then the unit has to be area of sale dependent [European/Canada] and not US.

Since I have not dabbled with these units, I also don't know how and which feature(s) has/have been incorporated into the main ECU. Earlier models of Lexus used dedicated controllers and progressively these have been pulled into central controller and that has necessitated the use of Muliplexing control and data communication on common wires.

Salim

Margate330

I can change from Celsius to Farenheight degrees on my soldering iron and basically any modern electronic device including my microwave oven.

-> So why in the world did Lexus think it was smart to make this feature unavailable in a Luxury car blows my mind, there must be a good reason but maybe not- I have no clue...

BTW- the ECM in the RX300 has a 16 bit microcontroller/processor so I'm sure it can handle the math of a simple conversion. lol